Tumor necrosis factor-alpha (TNF-α) is a potent cytokine, secreted primarily by activated monocytes and macrophages, that contributes to a variety of inflammatory disease states and is broadly involved in immunomodulation. TNF-alpha is processed from an immature, membrane-bound form to a mature, secreted form by a metalloproteinase called TNF-alpha converting enzyme, or “TACE.” See, R. A. Black et al., Nature 385:729–733 (February 1997); M. L. Moss et al., Nature 385:733–736 (February 1997); M. L. Moss et al., J. Neuroimmunol. 72:127–129 (February 1997). Inhibitors of the enzyme TACE block secretion of TNF-alpha.
TACE is a new member of a protein family called “ADAMs” (proteins which contain A Disintegrin And Metalloprotease domain; also called adamalysins). See, Wolfsberg et al., Dev. Biol. 169:378–383 (1995).
The TACE/ADAM family is composed of membrane proteins with structural homology to the snake venom metalloproteases and disintegrins. Snake venom disintegrins are a family of anticoagulant peptides with a high cysteine content. A new member of TACE/ADAM in Drosophila, called the kuzbanian gene (“KUZ”), was found to be involved in Drosophila neurogenesis (Rooke, J. et al., Science 273:1227–1231 (August 1996)).
Approximately 11–13 ADAM genes have now been identified, including fertilin alpha and beta (involved in the integrin mediated binding and fusion of egg and sperm; previously known as PH-30 alpha and beta), epididymal apical protein I, cyritestin, MDC (a candidate for tumor suppressor in human breast cancer), meltrin- (mediates fusion of myoblast fusion in the process of myotube formation), MS2 (a macrophage surface antigen), and metargidin. Typical ADAMs are cell surface proteins which consist of pro-, metalloprotease-like, disintegrin-like, cysteine-rich, epidermal growth factor-like repeat, transmembrane and cytoplasmic domains.
A new ADAM family gene, named ADAMTS-1, containing a disintegrin and metalloproteinase domain with thrombospondin (TSP) motifs, has now been shown to be closely associated with various inflammatory processes, as well as development of cancer cachexia. Kuno, K. et al., J. Biol. Chem. 272:556–562 (1997).
The disintegrin domain of ADAM family proteins functions in the prevention of integrin-mediated cell to cell and cell to matrix interactions, such as platelet aggregation, adhesion, and migration of tumor cells or neutrophils, and angiogenesis. Previously described disintegrins, such as contortrostatin (Trikha et al., Cancer Research 54:4993–4998 (1994) have been used to inhibit human metastatic melanoma (M24 cells) cell adhesion to type I collagen, vitronectin, and fibronectin, but not laminin. Further, contortrostatin inhibits lung colonization of M24 cells in a murine metastasis model.
The matrix metalloproteinases (MMPs) compose a family of structurally similar zinc-dependent enzymes that degrade all of the major components of the extracellular matrix. MMPs include the collagenases, gelatinases A and B, the stromelysins, matrilysin, metalloelastase, and the membrane-type matrix metalloproteinases. Over-expression and activation of MMPs have been linked with a range of diseases, such as arthritis, cancer, and multiple sclerosis. Regarding cancer, although MMPs classically have been implicated in basement membrane destruction associated with late-stage tumor cell invasion and metastasis, one MMP member, matrilysin, has recently been shown to be expressed in early stage human colorectal tumors. (C. L. Wilson et al., Proc. Natl. Acad. Sci. USA 94:1402–1407 (February 1997)).
Clearly, members of the TACE/ADAM family of proteins have a high potential for becoming valuable therapeutically and diagnostically. ADAM proteins, peptides derived from the sequence of ADAM proteins, and ADAM protein antagonists may become desirable components of molecular methods of assisting or preventing fertilization. Furthermore, specific TACE/ADAM proteins or derivatives may be useful in the detection and prevention of muscle disorders. TACE-like proteins also have an exciting potential in the treatment of inflammation, thrombosis, cancer, and cancer metastasis. TACE-like factors, or antagonists thereof, may also become useful agents in promoting macrophage or T-cell adhesion to matrices or cells' access to bound cytokines and other regulatory molecules.
Inhibitors of members of the matrix metalloproteinase (MMP) family (such as matrilysin) have been studied in the treatment or prophylaxis of cancer, cancer metastasis, as well as in the treatment of arthritis, corneal ulcers, pleural effusion, and multiple sclerosis. For a review on recent advances in matrix metalloproteinase research, see, Beckett, R. P. et al., DDT: 1:16–26 (January 1996).
Clearly, there is a need in the art for novel TACE-like and matrilysin-like molecules, exhibiting sequence relatedness to known metalloproteinases with recognized therapeutic and diagnostic usefulness.